package lec04.pm.gm.v2;

class QQ{
	long number;
	QQ[] friends;
	QQ[] blacklists;
	QQ[] strangers;
}
class WebPage{
	String url;
	WebPage[] hyperlinks;
}
public class Book {
	String name;
	String[] authors;
	double price;
	String press;
	Book[] refers;	
}
